European Journal of Clinical Investigation

Plasma free fatty acids (FFA) play important physiological roles in skeletal muscle, heart, liver and pancreas. However, chronically elevated plasma FFA appear to have pathophysiological consequences. Elevated FFA concentrations are linked with the onset of peripheral and hepatic insulin resistance and, while the precise action in the liver remains unclear, a model to explain the role of raised FFA in the development of skeletal muscle insulin resistance has recently been put forward. Over 30 years ago, Randle proposed that FFA compete with glucose as the major energy substrate in cardiac muscle, leading to decreased glucose oxidation when FFA are elevated. Recent data indicate that high plasma FFA also have a significant role in contributing to insulin resistance. Elevated FFA and intracellular lipid appear to inhibit insulin signalling, leading to a reduction in insulin‐stimulated muscle glucose transport that may be mediated by a decrease in GLUT‐4 translocation. The resulting suppression of muscle glucose transport leads to reduced muscle glycogen synthesis and glycolysis. In the liver, elevated FFA may contribute to hyperglycaemia by antagonizing the effects of insulin on endogenous glucose production. FFA also affect insulin secretion, although the nature of this relationship remains a subject for debate. Finally, evidence is discussed that FFA represent a crucial link between insulin resistance and β‐cell dysfunction and, as such, a reduction in elevated plasma FFA should be an important therapeutic target in obesity and type 2 diabetes.

Abstract. A highly specific monoclonal antibody directed against the C‐terminal part of glucagon‐like peptide‐1 (GLP‐1) was raised to immunohistochemi‐cally evaluate the distribution of GLP‐1 containing cells in the entire gastrointestinal tract including pancreas of rat, pig and man. In the pancreas GLP‐1 ‐immunoreactive cells were found variously shaped and predominantly located in the periphery of the islets. Ultrastructurally, GLP‐1 was co‐localized with gluca‐gon in the α‐granula of A‐cells and was mainly restricted to the electrondense core. In the intestine open type cells reaching the lumen via a slender apical process were stained with the GLP‐1 antibody. They occurred in all parts of the crypts but predominantly in the basal portion. The density of GLP‐1 immuno‐reactive cells varied between species in a characteristic order: rat > pig > man. In pig and human gut a large number of cells occurred in the distal jejunum and ileum. A continuous increase of cell densities was found from the proximal to the distal colon resulting in highest numbers in the rectum. In rats the highest cell density occurred in the ileum. Again, a continuous increase of GLP‐1‐positive cell numbers was evident from the proximal to the distal portion of small and large bowel. GLP‐1 was partly co‐localized with PYY. The GLP‐1 positive cells appeared electronmicrosco‐pically as L‐cells with the typical large granula. This morphological data indicates that GLP‐1‐releasing cells in the small intestine are appropriately positioned in the distal part to sense and respond to the presence of nutrients that have escaped the absorptive surface of the upper small intestine.

Abstract. A sensitive and specific radioimmunoassay was developed for the precursor‐specific peptide segment located at the amino end of bovine type III procollagen. Human material showed high cross‐reactivity in this assay. Two forms of human procollagen peptides were detected in body fluids. The larger peptide (45K) was found in serum and ascites, and resembled the whole precursor‐specific segment which is presumably released from human type III procollagen by a single enzymatic cleavage. The smaller peptide (10K) was found mainly in urine indicating that further degradation of circulating procollagen peptides is required prior to their passage through the kidney.

Compared to peptide concentrations in normal human serum, two to twenty‐fold increases were observed in all patients with alcoholic liver disease, in fifteen of seventeen patients with acute hepatitis, and in ten of fourteen patients with chronic active hepatitis. Much higher levels were detected in ascites fluid. Patients with rheumatoid arthritis and other diseases showed far smaller elevations of the serum peptide. In alcoholic liver disease peptide levels correlated well with inflammation and necrosis observed in liver biopsies, but not with other laboratory parameters.

Background To investigate whether microvascular function in skin is a valid model to study the relationships between cardiovascular risk factors and microvascular function, we investigated skin microvascular function in individuals with increased coronary heart disease (CHD) risk.

Materials and methods Forty‐six healthy White individuals aged 30–70 years were studied. Coronary heart disease risk was assessed with the use of the CHD risk score according to the Framingham Heart Study, which is based on the risk factors age, blood pressure, cigarette smoking, total cholesterol, HDL cholesterol and diabetes. Endothelium‐dependent and ‐independent vasodilation in skin were evaluated with laser Doppler after iontophoresis of acetylcholine and sodium nitroprusside. Videomicroscopy was used to measure recruitment of skin capillaries after arterial occlusion.

Results Coronary heart disease risk score (i.e. the 10‐year probability of CHD) varied from 1–37%. Microvascular function decreased with increasing quartiles of CHD risk (for acetylcholine‐mediated vasodilation: 687, 585, 420 and 326%, P = 0·002; for nitroprusside‐mediated vasodilation: 776, 582, 513 and 366%, P = 0·02; for capillary recruitment: 49·9, 44·6, 27·2 and 26·7%, P = 0·001). These trends were similar in men and women (P for interaction > 0·2) and independent of body mass index.

Conclusions Increased CHD risk is associated with an impaired endothelium‐dependent vasodilatation and capillary recruitment in skin, suggesting that microvascular function in skin is a valid model to study the relationships between cardiovascular risk factors and microvascular function.

Making sense of rapidly evolving evidence on genetic associations is crucial to making genuine advances in human genomics and the eventual integration of this information in the practice of medicine and public health. Assessment of the strengths and weaknesses of this evidence, and hence the ability to synthesize it, has been limited by inadequate reporting of results. The STrengthening the REporting of Genetic Association studies (STREGA) initiative builds on the STrengthening the Reporting of OBservational Studies in Epidemiology (STROBE) Statement and provides additions to 12 of the 22 items on the STROBE checklist. The additions concern population stratification, genotyping errors, modelling haplotype variation, Hardy–Weinberg equilibrium, replication, selection of participants, rationale for choice of genes and variants, treatment effects in studying quantitative traits, statistical methods, relatedness, reporting of descriptive and outcome data and the volume of data issues that are important to consider in genetic association studies. The STREGA recommendations do not prescribe or dictate how a genetic association study should be designed, but seek to enhance the transparency of its reporting, regardless of choices made during design, conduct or analysis.

Abstract. Scleroderma is a fibrotic disease occurring in a localized or systemic form. Disturbed regulation of connective tissue metabolism plays an important role in its pathogenesis. However, until now, most of the data available were obtained from studies of fibroblasts in culture and there is considerable doubt that fibroblasts in a monolayer reflect the in‐vivo situation. Using in‐situ hybridization with specific antisense RNAs on frozen sections of skin, cells were detected displaying enhanced messenger RNA levels for type I and type III collagen in patients with localized and systemic scleroderma. Activated fibroblastic cells were often located near blood vessels in the deep dermis of patients with early stages of the disease and were mostly surrounded by mononuclear cells. These findings are in agreement with the concept that the interaction of fibroblasts with ‘immunocompetent cells’ is crucial in the initial activation of connective tissue metabolism in fibrosis.

Abstract. We measured plasma sulphur amino acids in twenty‐two patients with chronic renal failure and compared the findings with those obtained in twenty‐two normal subjects. In fasting blood (08.00 hours) cysteine‐homocysteine mixed disulphide was significantly increased in the renal patients, mean values (± SD) being 8.2 ± 3.4 and 3.1 ± 1.0 μmol/l respectively (P < 0.001). The increase was positively correlated with reduced renal function, as assessed by serum creatinine (r= 0.62; P < 0.01). Homocystine was detected in nineteen patients, the mean concentration (± SD) being 1.7 ± 0.6 μmol/l; it was not found in any normal subject. Methionine levels were not different but there were significant increases in cystine (P < 0.001) and taurine (P < 0.05) in the patients. Similar values for these amino acids were found in a second blood sample drawn at 16.00 hours. Changes in the other neutral and acidic amino acids measured were in agreement with those reported in chronic azotaemia. We concluded that plasma levels of all the principal sulphur amino acids except methionine are elevated in chronic renal failure emphasizing the importance of the kidney in sulphur excretion. Prolonged accumulation of homocysteine and cysteine‐homocysteine mixed disulphide may be relevant to the development of accelerated vascular disease in patients with chronic renal failure by producing endothelial damage.